Panels



PANELS Filed June 27, 1956 cw l o m \J 5 mg {a W w W H z N M .n I I O I p W E E H W m E 4 B I 3 n I 2 2 m @E 4 2/ I'M J I m t ATTORNEY.

PANELS Edwin A. Neugass, Poteau, Okla.

Application June 27, 1956, Serial No. 594,167

17 Claims. (Cl. 40-130) The present invention relates generally to panels, and more particularly is directed to illuminated instrument panels, control panels and the like, as employed, for example, in airplanes. Y

Heretofore, it has been proposed, for example, in United States Letters Patent No. 2,518,726, issued August 15, 1950, to Shlenker, to provide an illuminated panel of the described character comprising a core or body of light transmitting plastic material, such as, methyl methacrylate, between two relatively thin sheets or layers of white, translucent materials, such as, pigmented cellulose acetate, and outer sheets or layers of black opaque material, such as, vinyl preferably having a matte finish to diminish glare, with the opaque layer at the front of the panel having openings therein in the form of desired indicia defined, under ambient illumination, by the contrast between the white of the translucent layer exposed at such openings and the black of the front opaque layer surrounding the openings. Further, panels of the kind disclosed in the above identified Letters Patent, have holes extending therethrough and receiving incandescent lighting bulbs from which light issues into the light transmitting core or body for transilluminating the translucent layer at the openings of the front opaque layer. In such panels, the openings remote from an incandescent light bulb will necessarily be illuminated with an intensity less than that of the illumination'of the openings in proximity to the light bulb. In order to obtain some degree of balancing of the intensity of illumination at openings located varying distances from the incandescent light source, l have previously proposed that black spotting be provided on the back surface of the light transmitting body or core in back of indicia defining openings located close to a light source or that the white layer on the back surface of the core or body be restricted to those areas in back of indicia defining openings remote from a light source, for example, as disclosed in my prior United States Letters Patent No. 2,660,824, issued December 1, 1953. However, such spotting of the back surface of the light transmitting core or body requires special evaluation and design for each instrument panel arrangement and, in many cases, requires an experimental test program to achieve the desired balancing of the intensity of illumination at the several indicia. Further, it is frequently impossible, due to equipment located beneath the panel, to install the incandescent lighting bulb fixtures either in sufficient numbers, or in the locations, required for uniform illumination throughout the panel and, in any case, incandescent lamps or light bulbs are not entirely reliable, particularly for use in airplanes, where the normal vibration that may be expected tends to accelerate the burning out of the filaments thereof.

Sylvania Electric Products, Inc, of Salem, Massachusetts, has developed devices that provide illumination by a phenomenon referred to as electroluminescence. Generally, in such devices, the electroluminescence results from the direct application of voltage across a phosnited States Patent phor or from the placement of a phosphor in an electric 7 2,791,050 Patented May 7, 1957 "ice 2 field. More particularly, one form of lighting device that has been developed, includes a plate of glass or other transparent material having a semi-transparent conductive coating on one side thereof, a metal sheet, and a phosphor, which may be a fired mixture comprising percent of zinc sulphide and 25 percent of zinc oxide activated by small amounts of halogens, copper and/or lead, and which is suspended in a solid dielectric sheet sandwiched between the conductive coating and the metal sheet so that, when an alternating voltage is applied between the metal sheet and conductive coating, the phosphor glows and provides light issuing through the glass sheet, for example, as disclosed in United States Letters Patent No. 2,566,349, issued September 4, 1951, to Mager.

In another form of electroluminescent lighting device that has been proposed, for example, in United States Letters Patent No. 2,684,450, issued July 20, 1954, to Mager and Lowry, two intermeshed metallic grids are applied to a face of a supporting plate and insulated from each other, and a phosphor, which may have the composition indicated above, is then applied over and between the intermeshed metallic grids on the supporting plate so that, when an alternating voltage is applied between the two metallic grids to create an electric field, the phosphor in the field will glow.

Existing electroluminescent devices or plates, typified by the above described forms, are not suitable for conversion into instrument or control panels merely by the provision of markings thereon, particularly when the panels are for military aircraft and the like that must satisfy the requirements of the United States Defense Department specification identified as MILP7788. Such instrument or control panels often have intricate peripheral configurations and need to be provided with numerous, often oddly shaped, openings therein to accommodate switch or instrument actuating arms or shafts and to expose the faces of instruments therebehind. Although intricate peripheral configurations and numerous oddly shaped openings can be easily formed in the plastic materials making up panels of the kind disclosed in Patent No. 2,518,726, which has been identified more fully above, the metal or supporting sheets of the above described electroluminescent devices or plates are not so easily fabricated and, in any case, providing an electroluminescent plate of the described character having the area of a complete aircraft instrument panel would, by reason of the cost of the materials and the relatively expensive procedures employed in its manufacture, be of almost prohibitive cost. Further, the materials available for defining the markings or indicia on the front face of an instrument or control panel and for changing the color of the emitted light, in accordance with the above identified military specification, can not be made to adhere reliably to the fired electroluminescent mixture, particularly when subjected to the environmental tests and the tests submitting the panels to extreme high and low temperatures, as required in that military specification. Finally, the voltage required to cause electroluminescence of the phosphor represents a hazard in an instrument or control panel unless adequate insulation is provided therefor.

Accordingly, it is an object of the present invention to provide instrument or control panels that avoid the above mentioned disadvantages of the existing laminated plastic panels illuminated by incandescent lamps and of converted electroluminescent plates, and that employ electroluminescent plates as the source of illumination while permitting conformance with the requirements of the above identified military specification.

More particularly, an object of this invention is to provide an instrument or control panel having sharply defined indicia on the front thereof which are all uniformly illuminated without regard to the respective locations of the indicia on the panel.

Another object is to provide control or instrument panels having indicia or markings illuminated by one or more electroluminescent plates, and wherein the panels are constructed and arranged for ease and economy of manufacture, to resist destruction or failure even when subjected to extreme temperatures or other climatic conditions, and to safely insulate the relatively high voltages required for operation of such electroluminescent plates.

In accordance with an. aspect of the present invention, a control or instrument panel having a front surface defined by a layer of black, opaque, preferably plastic material, a layer of white, translucent, preferably plastic material covered by the black opaque layer, withthe exception of those areas where the white translucent layer isexposed through openings in the opaque layer defining the desired markings or indicia, a relatively thick sheet or layer of clear acrylic material which may be dyed red and carry fluorescent dies to control the color of the emitted light and which is disposed in back of the white translucent layer, a back plate of relatively rigid insulating material which may also be an acrylic plastic and has recesses in its front face corresponding to the areas of the black, opaque front layer having indicia or marking defining openings therein, and tag-like, relatively small electroluminescent plates loosely received in said recesses of the back plate so that, when the various plastic sheets and layers, which are easily fabricated, are bonded or otherwise secured together and voltages are applied to the several tag-like electroluminescent plates, the latter uniformly illuminate all of the indicia defining openings.

The above, and other objects, features and advantages of the present invention will be apparent in the following detail description of illustrative embodiments thereof which is to be read in connection with the accompanying drawings forming a part hereof, and wherein:

Fig. 1 is a front elevational view of a panel embodying the present invention;

Fig. 2 is an enlarged, fragmentary sectional view taken along the line 2-2 of Fig. 1;

Fig. 3 is a sectional view similar to Fig. 2, but showing another embodiment of the invention;

Fig. 4 is a sectional view similar to Fig. 2, but showing still another embodiment of the invention.

Fig. 5 is a sectional view taken along the line 5--5 of Fig. 1; and i Fig. 6 is a front elevational view of a back plate included in the panel of Fig. l prior to its assembly with the other elements making up said panel.

Referring to the drawings in detail, and initially to Figs. 1 and 2 thereof, it will be seen that a panel embodying the present invention, and there generally identified by the reference numeral 10, includes a front layer 11 of a black, opaque material, which is preferably a plastic, for example, of the class of polyvinyl or vinyl resins or materials, their polymers or copolymers, having a matte finish and being either resilient or rigid. A layer 12 of white, translucent material underlies the front opaque layer 11 and may be formed of a clear plastic material, such as, a vinyl resin, having a dispersion of relatively large particles suspended therein as an emulsion, as more fully described in my prior United States Letters Patent No. 2,693,656, issued November 9, 1954, so that ambient light falling on the front surface of the layer 12 will be reflected forwardly and artificially pro duced red light entering the layer 12 at the back surface of the latter will be transmitted forwardly through the translucent layer.

In back of the translucent layer 12 there is a relatively thick sheet 13 of light transmitting material, for example, methyl methacrylate, and the sheet 13 of clear material may have a coating 14 of fluorescent dye on its backsurface, as shown in Fig. 2, so that when the sheet 13 is itself dyed red, red light will be transmitted therethrough from the source or sources hereinafter referred to in detail even though such sources normally emit blue light or light composed mostly of rays from the ultra-violet end of the spectrum. The fluorescent coating 14 is excited by the ultra-violet radiation and emits at least some red light for passage through the red dyed sheet 13.

As seen in Figs. 1 and 2, indicia or markings on the front of the panel 10 may be defined by suitably shaped openings 15 formed in opaque layer 11 and exposing the underlying translucent layer 12. By reason of the sharp color contrast between the white translucent layer 12 exposed at the openings 15 and the black opaque layer it surrounding said openings, the corresponding mark ings or indicia are clearly visible under ambient illumination. On the other hand, when artificial light is admitted to the sheet 13, red light transilluminates the translucent layer 12 at the openings 15 to provide a clear, glarefrec 'llumination of the corresponding indicia or markings, it being preferable to employ red light for such transillumination to avoid too great interference with the dark adaptation or night vision of the pilot or other observer reading the panel.

As indicated in United States Letters Patent No. 2,594,- 081, issued April 22, 1952, to Shlenker, the exposed surface 16 of the translucent layer 12 may be recessed in back of the front face of opaque layer 11 at each opening, as in Fig. 2; or, as indicated in the panel 10:: of Fig. 3, the translucent layer 12a may be made to project forwardly into the opening of the opaque layer lla until the exposed surface of the translucent layer is flush with the front face of the opaque layer; or still further, as indicated in the panel 10b of Fig. 4, the translucent layer 12/) may project forwardly through the opening of the opaque layer 11b so that the exposed surface 16b of the translucent layer is disposed forwardly beyond the front face of the opaque layer.

Further, at certain areas of the panel 10, it may be de sirable to expose the front face of the light transmitting sheet 13 by cutting away both the front opaque layer 11 and the translucent layer 12, as at 16 (Figs. 1 and 5), for example, where it is desired to transmit light for illuminating an instrument dial and pointer.

It will be noted that, in an instrument or control panel of the described character, the indicia or markings thereon, and the other locations where light may be required, are usually concentrated in separated areas of the panel. In accordance with the present invention, electroluminescent lighting devices or plates of the kind described above, are provided in back of the coated or dyed sheet 13 of light transmitting material only in those areas where light may be required. For example, in the panel 10 of Fig. I, an electroluminescent lighting plate 17 (shown in broken lines) is disposed in back of the sheet 13 over the area of the panel covered by the legend Wing De-Icer, an electroluminescent lighting plate 18 (shown in broken lines) extends over the area covered by the legends On and Off, and an electroluminescent lighting plate 19 (shown in broken lines) extends over the area of the opening or clear space 16. Since the several electroluminescent lighting plates 17, 18 and 19 may all be energized by the same voltage, it is apparentv that the light emitted therefrom into the light transmitting sheet 13 therein front will be uniform throughout the illuminated parts of the panel and there is no need to resort to the light balancing expedients previously described herein.

The panel 10 is completed by a backing sheet 20 of insulating material, for example, of an acrylic resin such as methyl methacrylate. The backing sheet 20 is applied against the back surface of the light transmitting sheet 13 and has suitable recesses formed in its front surface to accommodate the above mentioned electro luminescent lighting plates. For example, as shown in Fig. 6, the front surface of backing sheet 20 may be formed with recesses 21, 22-.and 23 ..to. accommodate :the lighting plates 17, 18 and 19, respective1y." The electrical circuits for connecting the several lighting plates in parallel or in series, as desired, may be printed on the front surface of the backing sheet 20 prior to final assembly of the panel 10, or, as indicated on Fig. 6, a suitable pattern of grooves 24 may be formed in the front surface of sheet 20 extending to the several recesses 21, 22 and 23 to receive electric conductors 25 (Fig. 1) for connecting the electroluminescent lighting plates to a suitable source of voltage. o

It is to be noted that the recesses 21, 22 and 23 are larger in all directions, that is, in depth and in the plane of the sheet 20, than the corresponding lighting plates 17, 18 and 19 so that, when the panel is...assembled, substantial clearance will exist around,- and-in front and in back of, each of the electroluminescent lighting plates within its corresponding rece ss, asshown in Figs. 2 and 5, thereby to permit expansion and contraction of the lighting plates and of the plastic sheets and layers of the panels at different rates in response to extremechanges in temperature without giving rise to internal stresses within the panel causing fracture or other damage, such as, for example, separation of the several sheets and layers making up the panel.

In producing the above described panel, the layers 11 and 12 and the sheet 13 are joined together to form a sandwich or lamination either by adhesive or by the application of heat and pressure, then the backing sheet or plate 20, having the electroluminescentlighting plates D1 of the layers 11 and 12 and the sheet 13, disposed in front of each electroluminescent lighting plate, is substantially equal to the thickness D2 of the backing sheet 20 at each of the recesses in the latter,'so that the plastic materials in front and in back of each lighting plate are of the same thickness and the heat generated by the lighting plates or the exposure of the panel to extreme low temperatures will not cause bending or warping of the panel.

The indicia defining openings 15 and othel light emitting openings, such as, the opening 16, may be formed, 1

as by engraving, either after the initial laminating operation, joining together the layers 11 and 12 and the sheet 13, or after the initial lamination and the backing sheet have been joined together. In the case of the modifications illustrated in Figs. 3 and 4, the flush or raised indicia or markings may be formed in the manner indicated in United States Letters Patent No. 2,602,036, issued July 1, 1952, to Sullivan.

Following the assembly of the several layers and sheets making up the panel 10, the necessary holes are formed therethrough, for example, as at 24, and 26 (Fig. 1), to receive the shafts, rods and the like extending from control knobs or handles or from pointers to related controls, switches or instruments and the like to be mounted in back of the panel, and the panel is given the desired peripheral contours. Finally, a black epoxy coating is applied to the edges of the panel and to the surfaces of the above mentioned holes to prevent the escape of light from the panel except at the intended places.

It is apparent that the electroluminescent lighting plates may be stocked in the form of relatively small tags of various standard dimensions and platforms so that, in producing panels having different forms and lighting requirements, suitable standardized tags can be selected for use in the panel, and all machining of holes and contoursis restricted tothe relatively easily worked plastic materials of the layers 11 and 12 and the sheets 13 and 20, thereby greatly decreasing the cost of the panel when compared .With a panel or sign wherein the electroluminescent lighting plate is itself formed with the necessary openings and contours. Further, since each electroluminescent lighting plate is completely encased in insulating plastic material, panels embodying this invention completely eliminate any shock hazard.

Although illustrative embodiments of the invention have been described in detail herein and are shown in the accompanying drawings, it is to be understood that the invention is not limited to these precise embodiments, and that various changes and modifications may be effected in the latter without departing from the scope or spirit of .theinvention, except as defined in the appended claims.

, What is claimed is: I

1. A panel comprising asheet of transparent material with a. layer of translucent material superimposed on the front face thereoffan outer layer of opaque material superimposed over said translucent layer and having openings therein through which the latter is exposed to define indicia, a backing sheet disposed against the back surface of said transparent sheet and having at least one recess in its front face at the areas of the panel having said indicia defined thereon, and an electroluminescent lighting plate disposed in said recess to emit light forwardly into said transparent sheet to transilluminate the translucent layer at said openings in the opaque layer.

2. A panel as in claim 1; wherein the front surface of said translucent layer, at the areas thereof exposed through said openings in the opaque layer, is flush with the back surface of said opaque layer.

3. A panel as in claim 1; wherein said translucent layer, extends forwardly into said openings of the opaque layer and the front surface of the translucent layer, at the areasthereof exposed through said openings in the opaque layer, is flush with the front surface of said opaque layer. I

'4. A panel as in claim 1; wherein said translucent layer extends forwardly through said openings of the opaque layer and the front surface of the translucent layer, at the areas thereof exposed through said openings, projects forwardly beyond the front surface of said opaque layer to define raised indicia.

5. A panel comprising a sheet of transparent material with a layer of translucent material superimposed on the front face thereof, .an outer layer of opaque material superimposed over said translucent layer and having openings therein through which the latter is exposed to de fine indicia, a backing sheet disposed against the back surface of said'transparent sheet and having at least one recess-in its front face at the areas of the panel having said indicia defined thereon, and an electroluminescent lighting plate disposed in said recess to emit light forwardly into said transparent sheet to transilluminate the translucent layer at said openings in the opaque layer, said electroluminescent lighting plates fitting loosely in the related recesses of said backing sheet so that said lighting plates and said layers and sheets can expand and contract at different rates due to temperature changes without causing excessive stresses to be produced within the panel.

6. A panel comprising a sheet of transparent material with a layer of translucent material superimposed on the front face thereof, an outer layer of opaque material superimposed over said translucent layer and having openings therein through which the latter is exposed to define indicia, a backing sheet disposed against the back surface of said transparent sheet and having recesses in its front face at the areas of the panel having said indicia defined thereon, and electroluminescent lighting plates disposed in said recesses to emit light forwardly into said transparent sheet to transilluminate the trans lucent layer at said openings in the opaque layer, said layers and sheets being of materials having substantially equal coefiicients of expansion, and the combined thicknesses of said opaque and translucent layers and of said transparent sheet being substantially equal to the thickness of said backing sheet at said recesses in the latter to avoid bending and warping of the panel due to heating by said lighting plates and due to subjecting of the panel to extremely low temperatures.

7. A panel comprising a front layer of opaque material, a layer of translucent material disposed against the back of said opaque layer, said opaque layer having openings in selected regions thereof through which said translucent layer is exposed to define indicia, abody of transparent insulating material disposed against the back of said translucent layer and being substantially coextensive with said translucent and opaque layers, said transparent body having hollow spacesenclosed therein which are substantially coextensive with said selected regions of the opaque layer, and electroluminescent lighting means disposed in each of said hollow spaces to direct light forwardly through said transparent body into said translucent layer for transilluminating the latter at said openings in the related region of said opaque layer.

8. A panel comprising a front layer of opaque material, a layer of translucent material disposed against the back of said opaque layer, said opaque layer having openings in selected regions thereof through which said translucent layer is exposed to define indicia, a body of transparent insulating material disposed against the back of said translucent layer and being substantially coexand a backing sheet having recesses in the front surface thereof defining said hollow enclosed spaces when said backing sheet is applied against the back surface of said sheet forming the forward portion of the body.

9. A panel as in claim 8; further comprising electric conducting means disposed between the confronting surfaces of said backing sheet and said sheet forming the forward portion of the body.

10. A panel as in claim 9; wherein said electric conducting means includes a "printed circuit on one of said confronting surfaces. V

11. A panel as in claim 9; wherein said front surface of the backing sheet has grooves therein communicating 8 with said recesses, and said electric conducting means includes conductors disposed in said grooves and connected m said electroluminescent lighting means in said spaces.

l2. Apa'nel as in claim 8; wherein said opaque and translucent layers and said sheets of the transparent body are of plastic materials, and the combined thickness of said layers and of said sheet forming the forward portion of the body is substantially equal to the thickness of said backing sheet at each of said recesses in the latter.

13. A panel as in claim 12; wherein the dimensions of said recesses in the plane of said backing sheet and in the direction normal to said plane are substantially larger than the corresponding dimensions of the related electroluminescent lighting means so that the latter are normally loosely disposed in said spaces to avoid the development of excessive stresses within the panel when said layers and sheets, on the one hand, and said lighting means, on the other hand, expand and contract at different rates in response to temperature changes.

14. A panel as in claim 8; wherein the transparent material of said sheet forming the forward portion of the body is dyed red to transmit red light into said translucent layer.

15. A panel as in claim 8; wherein said sheet forming the forward portion of the body has a coating of red fluorescent pigment on the back surface thereof so that only red light is transmitted from said lighting means into said translucent layer.

16. A panel of the described character comprising a lamination including a front layer of opaque material, a layer of translucent material disposed against the back of said opaque layer, said opaque layer having openings in selected regions thereof through which said trans lucent layer is exposed to define indicia and a sheet of transparent material disposed against the back of said translucent layer, a backing sheet having recesses in the front surface thereof which are coextensive with said selected regions of the opaque layer when said backing sheet is applied against the back of said lamination and which then define enclosed hollow spaces, and electroluminescent lighting plates disposed in said enclosed hollow spaces to emit light forwardly into said transparent sheet for transmission by the latter to transilluminate said translucent layer at said openings in the related regions of said opaque layer.

17. A panel as in claim 16; wherein said opaque and translucent layers are of contrasting colors to render said indieia clearly visible when the front of the panel is viewed under ambient illumination.

No references cited.

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